The inventor of sure-fire failures leads such an abysmal life that he creates a second identity, that of a dashing, debonair womaniser.
| Actor | Role |
|---|---|
 Donald PleasenceArthur Brownjohn / Sir Easonby 'E' Mellon | Arthur Brownjohn / Sir Easonby 'E' Mellon |
 Shelley WintersHester Green | Hester Green |
 Terry-ThomasClennery Tubbs | Clennery Tubbs |
 Tammy GrimesLady Joan Mellon | Lady Joan Mellon |
 Judith ArthyPatricia Parker | Patricia Parker |
 Michael BatesMr. Harrington | Mr. Harrington |
| PPeter BaylissDr. Hubbles | Dr. Hubbles |
 Joan BenhamMrs. Payne | Mrs. Payne |
 Erik ChittyUncle Ratty | Uncle Ratty |
 Margaret CourtenayClare Brownjohn | Clare Brownjohn |
 Mark EdenJack Parker | Jack Parker |
 Robin EllisAmes | Ames |
 Raymond HuntleyGeorge Payne | George Payne |
| PPatsy SmartMiss Bonnamie | Miss Bonnamie |
 Oliver TobiasPeter 'Bobo' Jackson | Peter 'Bobo' Jackson |
 Keith MarshLillywhite | Lillywhite |
| TTony HollandHimself on Television - Muscleman (uncredited) | Himself on Television - Muscleman (uncredited) |